Dirty Brass. This color is accomplished by burning the metal to the point that it releases its impurities and self colorizes. This patina occurs from within, no chemical was added to the surface.
Black Sterling. Black Sterling is acheived by the oxidization of sterling silver. This blackened state will fade or scratch off over time but we will be happy to help teach you how to re-oxidize your pieces if you are interested (it is a very easy process). Additionally, please note that Black Sterling tends to look darker in photograph than in person.